The present invention relates to a digital process controller and more particularly to a digital process controller for controlling long period industrial processes. Industrial process controllers heretofore known to the art which are capable of controlling industrial processes requiring several hours or days, have frequently been electro-mechanical, such as clock operated switches or paper or magnetic tape readers. Such electro-mechanical devices, when employed in an industrial environment, have been extremely bulky and cumbersome. Further, reliability in an industrial environment of such electro-mechanical devices has been difficult to achieve. As a result, many processes, such as heat treatment and annealing of metals, has been controlled manually. Since manual control is subject to human error, there has long been a demand for a simple, reliable, inexpensive automatic process controller suitable for use in connection with industrial processes which may require a period of up to several days for completion.